A “standard list of metasyntactic variables used in syntax examples” often used in the United States is: foo, bar, baz, qux, quux, corge, grault, garply, waldo, fred, plugh, xyzzy, thud. The word foo occurs in over 330 RFCs and bar occurs in over 290. […]
Due to English being the foundation-language, or lingua franca, of most computer programming languages these variables are also commonly seen even in programs and examples of programs written for other spoken-language audiences.